There are many types of bottle valves used during various applications such as with autoclaves, propane tanks, water bottles and nitrous-oxide for auto racing; depending on the use, a bottle valve is a device that generally measures, regulates and distributes the flow of a liquid or gas from a contained element or bottle into a flow path for release and use. A valve is technically a fitting used to obstruct or direct the flow of the contents, determining pressure and amount as well as flow direction.
Manual valves such as a bottle valve work by allowing or preventing the flow of liquid. Valve designs include a rotating valve that moves within the passageway to stop flow, a seal or plug valve the obstructs the flow, a manually inserted plug that controls ebb and flow, a pinching obstruction that prevents flow and rotating valves such as ball, butterfly and gate valves.
Bottle valves can be manually or automatically controlled. Other valve types feature quarter-turn and hand-wheel valves. Some type of valve is used in everything from aerosol cans to farming irrigation.
The most simplistic definition of how a valve works is a freely hinged flap that drops to prevent flow in one direction and is pushed to open flow in another direction.